COMPOSITIONS AND METHODS FOR SCREENING T CELLS WITH ANTIGENS FOR SPECIFIC POPULATIONS
Compositions and methods for isolating patient-derived antigen-specific T cells include an antigen complex having a polynucleotide barcoded nanoparticle sorting agent complexed with a peptide-loaded streptavidin major histocompatability complex (MHC) tetramer, the barcoding technology allowing for high fidelity screening of a library of the antigen complexes to readily isolate and identify antigen-specific T cells.
The present application claims priority to and the benefit of U.S. Provisional Application Ser. No. 62/169,337 filed on Jun. 1, 2015, entitled “A Method for Pairing the T Cell Receptor Sequence with Cognate Antigen from Diverse Antigen Specific T Cell Populations,” the entire content of which is incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTThis invention was made with government support under Grant No. CA151819 and CA1710689 awarded by the National Institutes of Health. The government has certain rights in the invention.
INCORPORATION BY REFERENCEThe instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Sep. 14, 2016, is named 122720US_SL.txt and is 65,986 bytes in size.
BACKGROUNDNeoantigens from tumor cells are peptide fragments of mutated proteins that contain a mutation, and are capable of being presented in the cleft of Major Histocompatibility Complex (MHC) Class I molecules on the surfaces of cells within the tumor, where they can be surveyed by CD8-positive T cells. The tumor-specificity of neoantigens, coupled with the ability of neoantigen-specific T cells to specifically kill cancer cells, has made tumor neoantigens increasingly important for cancer immunotherapy. Additionally, T cell receptors (TCRs) that recognize specific neoantigens are candidates for TCR-engineered cell based therapies for targeting infections that produce neoantigens.
Putative neoantigens have been previously identified by tumor exome analysis, and subsequently rank-ordered according to their MHC binding strength using in silico analysis. However, finding which candidate neoantigens are actually promoting T cell tumor infiltration is challenging for several reasons. First, a patient tumor that has a mutation density of 10 per 1 million expressed DNA base pairs might be predicted to have on the order of 50 putative neoantigens that exhibit a binding constant (Kd) to a given human leukocyte antigen (HLA) genotype MHC of 500 nM or lower. Furthermore, any particular neoantigen-specific T cell population is likely to exist in very low abundance in a patient, rendering isolation and/or identification of neoantigen-specific T cells very difficult. Related challenges to these issues include the pairing of neoantigens to their cognate TCRs. Nevertheless, these neoantigen-T cell pairing interactions are at the core of cancer immunotherapy, and so there has been significant effort towards meeting these challenges. Previous approaches for neoantigen-specific T cell pairing have shown to be laborious, non-quantitative, and/or they may only identify one or two T cell populations per HLA genotype due to limited sensitivity.
SUMMARYIn some embodiments of the present invention, an antigen complex includes a nanoparticle sorting agent including a nanoparticle, a polynucleotide detection tag having at least one coding region, the polynucleotide detection tag being conjugated to the nanoparticle, and a first polynucleotide hybridization domain conjugated to the polynucleotide detection tag. The antigen complex also includes a peptide-loaded streptavidin major histocompatability complex (MHC) tetramer, including a modified streptavidin protein, four biotin-modified MHC proteins each independently conjugated to the modified streptavidin protein, an antigen peptide bound to the biotin-modified MHC proteins, and a second polynucleotide hybridization domain different from the first polynucleotide hybridization domain and conjugated to the modified streptavidin protein, where the nanoparticle sorting agent is linked to the peptide-loaded streptavidin MHC tetramer by hybridization of the first polynucleotide hybridization domain to the second polynucleotide hybridization domain.
In some embodiments of the present invention, a library of antigen complexes include a plurality of the antigen complexes disclosed above where each of the antigen complexes has a different antigen peptide and different polynucleotide detection tag than any other of the antigen complexes in the plurality of antigen complexes.
In some embodiments of the present invention, a kit for detecting neoantigen-specific T cells includes a polynucleotide detection tag including at least one coding region, where the polynucleotide detection tag is conjugated to a nanoparticle, the kit also includes a decoding polynucleotide that is capable of hybridizing to the at least one coding region of the polynucleotide detection tag. In some embodiments, the kit also includes a displacement polynucleotide capable of hybridizing to the decoding polynucleotide. In some embodiments, the kit includes at least one of the polynucleotide detection tag sequences of
In some embodiments of the present invention, a method for isolating neo-antigen-specific T cells for a tumor in a subject includes identifying candidate T cell epitopes for the tumor using a major histocompatiblity complex (MHC) binding algorithm, synthesizing antigen peptides corresponding to the candidate T cell epitopes, preparing the library of antigen complexes using the antigen peptides, incubating the library of antigen complexes with TILs or PBMCs from the subject, and separating paired T cells from unpaired T cells, the paired T cells comprising those T cells that have paired with any of the antigen peptides of any of the antigen complexes in the library of antigen complexes.
In some embodiments of the present invention, the method for isolating neo-antigen-specific T cells for a tumor in a subject as above, also includes adding the paired T cells to a microfluidic device to separate the paired T cells into individual paired T cells, and detecting the sequence of the at least one coding region of the polynucleotide detection tag of the antigen complex of each individual paired T cell. In some embodiments, the detecting the sequence of the at least one coding region of the polynucleotide detection tag of the antigen complex of each individual paired T cell includes incubating the polynucleotide detection tag of each individual paired T cell with at least two labeled decoding polynucleotides, and detecting presence of a hybridized labeled decoding polynucleotide to thereby determine the sequence of the at least one coding region of the polynucleotide detection tag.
In some embodiments of the present invention, the method for isolating neo-antigen-specific T cells for a tumor in a subject is as above, in which the least one coding region of the polynucleotide detection tag of the antigen complex includes at least two coding regions, and detecting the sequence of the at least two coding regions of the polynucleotide detection tag of the antigen complex of each individual paired T cell includes incubating the polynucleotide detection tag of each individual paired T cell with at least two first labeled decoding polynucleotides, detecting presence of one or more first hybridized labeled decoding polynucleotides to thereby determine the sequence of a first one of the at least two coding regions of the polynucleotide detection tag, incubating the one or more first hybridized labeled decoding polynucleotides with one or more displacement polynucleotides to remove the first labeled decoding polynucleotides from the first hybridized labeled decoding polynucleotide to yield a partially decoded polynucleotide detection tag, incubating the partially decoded polynucleotide detection tag with one or more second labeled decoding polynucleotides, and detecting presence of a second hybridized labeled decoding polynucleotide to thereby determine the sequence of a second one of the at least two coding regions of the polynucleotide detection tag of the antigen complex of each individual paired T cell.
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T-cell mediated immunity is characterized by the activation of antigen-specific cytotoxic T cells that are able to induce apoptosis in cells that display epitopes of foreign antigen in a major histocompatibility complex (MHC) on their surface, as depicted in
Currently known methods for screening neoantigen-specific T cells are time consuming and/or have low sensitivity, and most methods identify only a few T cells per HLA genotype. Embodiments of the present invention include recombinant antigen-loaded MHC compositions and facile decoding methods for high fidelity, rapid, and non-destructive isolation and identification of patient-specific T cell populations targeted to patient-specific antigens, e.g., neoantigens. Embodiments of the present invention include a nanoparticle (NP) having a unique polynucleotide barcode (NP) linked to a unique recombinant antigen-MHC complex. Utilizing the barcoded nanoparticle-antigen-MHC complex, T cells that pair with the antigen-MHC complex are then isolated in this antigen-MHC-T cell complex by selective isolation of the nanoparticle. The isolated antigen-MHC-T cell complex may then be transferred to a cell trapping platform to separate individual antigen-MHC complex-T cells. According to embodiments of the present invention, the unique barcode for each isolated NP is identified by in situ amplification or using fluorescently labeled barcode sense strand “readers”. Using this nanoparticle isolation and barcode identification methodology, the individual antigen-MHC-T cell complex is identified, but is not destroyed. Accordingly, the isolated T cell is available after identification as a valuable source for further characterization (e.g., tumor biomarker analysis) or for further propagation. Further growth of the T cell results in an enriched population of patient-derived T cells targeted to the patient-specific antigens. This population of patient-derived T cells targeted to the patient-specific antigens may be used for adoptive cell transfer into the patient as a means of immunotherapy targeting the tumor or pathogen.
Compositions according to embodiments of the present invention include a recombinant antigen-MHC complexed with a barcoded nanoparticle (NP) sorting agent to form a barcoded NP-antigen-MHC complex. The barcoded NP-antigen-MHC complex is modular in form as schematically shown in
In silico analysis can be used to identify neoantigens. The in silico analysis for identifying putative neoantigens requires the genomic (DNA) or exomic (RNA) sequence of the tumor, virus, or bacteria in the patient. As the majority of viruses and bacteria found in patients are not unique to one patient, the genome sequences of these pathogens may be known and the available sequence data may be used. Nonetheless, both unknown (new) and previously identified viruses and bacteria may be isolated from a patient (e.g., from a blood sample) for DNA or RNA sequencing.
As tumor cancers include patient-specific mutations, DNA or RNA sequencing of tumor cells from a patient's tumor biopsy or blood sample is carried out as an initial step. Using the example of tumor neoantigens, according to embodiments of the present invention, identification of tumor neoantigens specific to a patient includes DNA and/or RNA sequencing as well as HLA-typing of tumor cells from a tumor biopsy or a blood sample of the patient. For somatic mutation identification (i.e., somatic mutation calling), DNA or RNA sequencing is also performed on a matched normal patient tumor or blood sample. The collective tumor-normal sequencing data are then input into at least one (e.g., two or three) algorithmic program (e.g., MuTect v1.1.7, Varscan2 Somatic (V2.3.6), and/or the GATK-HaplotypeCaller (HC, v3.3)) to identify somatic mutations that putatively express (correspond to) neoantigens. In some embodiments of the present invention, for patients having a tumor with low mutation burden, all of the in silico identified somatic mutations may be utilized to form a set of candidate tumor neoantigens for T cell screening. Alternatively, while all identified somatic mutations may be assayed, numerous somatic mutations may be identified in patients having a tumor with a high mutation burden, and therefore, it may not be efficient or necessarily effective to screen all of the identified mutations. Accordingly, in some embodiments of the present invention, the somatic mutations identified in silico are ranked with the highest ranked somatic mutations being observed by at least three algorithmic programs, followed by at least 2 algorithmic programs. In order to screen a manageable number of candidate neoantigen peptides, the patient's HLA type is determined from the tumor exome sequencing data using software for HLA typing (e.g., ATHLATES). Using software (e.g., the NetMHC3.4 server) for the patient-specific HLA type, putative neoantigenic sequences from the patent's biopsied tumor or blood sample are identified.
Embodiments of the present invention include a recombinant antigen-MHC complex that is capable of pairing with cognate T cells. As used herein, “antigen complex,” “antigen-MHC,” “antigen-MHC complex,” “recombinant antigen-MHC complex,” “peptide MHC,” and “p/MHC,” are used interchangeably to refer to a recombinant major histocompatibility complex with a peptide in the antigen binding groove. As used herein, “antigen” includes any antigen including patient-specific neoantigens.
A recombinant antigen-MHC complex according to embodiments of the present invention includes a recombinant MHC molecule. In some embodiments of the present invention, the MHC complex may be an MHC Class I (MHC I) complex that pairs with CD8-positive (CD8+) T “killer” cells. In other embodiments of the present invention, the MHC complex may be an MHC Class II (MHC II) complex that pairs with CD4+ “helper” T cells. The antigens presented by MHC Class I complexes are cytosolic proteins, while antigens presented by MHC Class II complexes are derived from extracellular proteins. As tumor cells are endogenously derived cells expressing mutations, tumor antigens are commonly presented by MHC Class I molecules, thereby pairing with CD8+ T cells. Similarly, viral proteins are endogenously expressed from a patient's cells, and are also presented by MHC Class I molecules to CD8+ T cells. Bacterial cells, however, express proteins using their own cellular machinery, which upon infection in a patient, are considered exogenously expressed and are presented by the patient's MHC Class II molecules to CD4+ T helper cells. MHC class III molecules include other immune components, such as complement components (e.g., C2, C4, factor B) and some that encode cytokines (e.g., TNF-a) and also heat shock proteins (hsps).
According to embodiments of the present invention, the MHC I or MHC II molecule of the recombinant antigen MHC complex is synthesized to correspond to the patient's HLA type. Polymorphisms are found in both MHC I and MHC II molecules. The MHC Class I molecules are heterodimers made of two polypeptide chains, α and β2-microglobulin (b2m). The α chain has three domains including α1, α2, and α3. The α and b2m chains are linked noncovalently via interaction of b2m and the α3 domain of the α chain. The α chain is polymorphic and is encoded by the HLA gene complex while the b2m subunit is not polymorphic and is encoded by the b2m gene. Assembly of the a and b2m chains is stabilized by the presence of a 9-11 amino acid peptide antigen loaded in the antigen binding groove on the surface of the α1 and α2 domains. According to embodiments of the present invention, patient-specific MHC class I antigens are presented on recombinant MHC class I complexes corresponding to the patient's HLA type. For example, the MHC I a chain is encoded by the HLA-A, HLA-B, or HLA-C gene. Each of the HLA-A, HLA-B, and HLA-C genes express allele-specific subtypes some of which are shown in Table 7 in Example 19.
The MHC Class II molecules are heterodimers made of two polypeptide chains, α and β. The α and b chains each have two domains: α1 and α2, and β1 and β2, respectively. Both the α and β chains are polymorphic and are encoded by the HLA gene complex. Assembly of the a and β chains forms an antigen binding groove on the surface of both the α1 and β2 domains with antigen peptide lengths from 11 to 30 amino acids. According to embodiments of the present invention, patient-specific MHC class II antigens are presented on recombinant MHC class II complexes corresponding to the patient's HLA type. For example, the HLA genes include HLA-DM, HLA-DO, HLA-DQ, and HLA in which the MHC II a chain is encoded by the HLA-A-DMA, HLA-DOA, HLA-DPA1, HLA-DQA2, or HLA-DRA gene and the β chain is encoded by HLA-DMB, HLA-DOB, HLA-DPB1, HLA-DQB1, HLA-DQB2, HLA-DRB1, HLA-DRB3, HLA-DRB4, or HLA-DRB5 gene.
In some embodiments of the present invention, the recombinant MHC molecule is an MHC Class II molecule expressed and loaded with a candidate antigen peptide as described in Novak et al., 1999, J. Clin. Invest. 104:R63-R67, the entire contents of which are herein incorporated by reference.
In some embodiments of the present invention, the recombinant MHC molecule is an MHC Class I molecule expressed as a conditional ligand. As the MHC class I molecule is unstable in the absence of peptide (i.e. antigen peptide), a recombinant MHC Class I molecule is expressed with a peptide having a cleavable moiety, that upon irradiation with UV light dissociates from the complex and disintegrates. However, if the UV disintegration of the cleavable peptide is performed in the presence of a “rescue peptide,” the rescue peptide will readily replace the UV irradiated peptide in the binding groove, as depicted in
In some embodiments of the present invention, the recombinant MHC molecule is a tetramer complex of four MHC molecules each loaded with the same candidate antigen peptide. Since most neoantigens have low binding affinities (Kd) for MHC proteins (e.g., 500 nM or lower) a tetrameric MHC complex allows for increased binding avidity, thereby increasing the sensitivity of this antigen-MHC tetrameric probe for pairing with low abundant cognate T cells. In some embodiments of the present invention, an MHC tetramer is formed using modified streptavidin conjugated with four biotin-modified MHC molecules. The streptavidin is modified to enable binding of a polynucleotide (e.g., DNA or RNA) linker. Modification of the streptavidin includes a binding moiety that can pair with (e.g., covalently bind to) a corresponding cognate binding moiety linked to the polynucleotide molecule. Any suitable pair of binding moieties may be used to modify streptavidin and the polynucleotide for linkage. Non-limiting examples of binding moiety pairs include a thiol group (e.g., cysteine) and maleimide, adamantane and cyclodextrin, an amino group and a carboxy group, and an azido group and alkynl group (i.e., click chemistry). An example of a cysteine-modified streptavidin linked to a maleimide-modified DNA hybridization domain (the “DNA-labeled tetramer”) is shown in
One of the current challenges with screening multiple antigen-MHC-T cell pairings is the isolation and identification of the T cell receptor epitope corresponding to the paired peptide antigen. Embodiments of the present invention include a modified nanoparticle linked to a polynucleotide detection tag (i.e., the barcode), where the polynucleotide detection tag includes at least one coding region. This complex, as well as the method of using the complex, is also referred to as nanoparticle-barcoded nucleic acid cell sorting (NP-barcoded NACS) and a nanoparticle sorting agent. In some embodiments, the nanoparticle is magnetic for isolation using a magnet. In some embodiments, the nanoparticle is a 1 um to 15 um polystyrene particle isolated by gravity. According to embodiments of the present invention, the nanoparticle is modified with a binding moiety for linking to the polynucleotide coding region. Modification of the nanoparticle includes a binding moiety that can pair with (e.g., covalently bind to) a corresponding cognate binding moiety linked to the polynucleotide molecule. Any suitable pair of binding moieties may be used to modify the nanoparticle and the polynucleotide detection tag for linkage. Non-limiting examples of binding moiety pairs include a thiol group (e.g., cysteine) and maleimide, adamantane and cyclodextrin, an amino group and a carboxy group, and an azido group and alkynl group.
Embodiments of the present invention include a barcoded-nanoparticle complex where the barcode is a polynucleotide detection tag made of coding regions that provide a unique antigen-specific sequence for identification after T cell isolation. As used herein, a “coding region” is a set of nucleotides with a unique and specific sequence that is separate from another polynucleotide. In some embodiments, one polynucleotide coding region is made of 5 to 25 nucleotide basepairs. In some embodiments, one polynucleotide coding region is made of 7 to 25 nucleotide basepairs, 8 to 25 nucleotide basepairs, 9 to 25 nucleotide basepairs, 10 to 25 nucleotide basepairs, 10 to 20 nucleotide basepairs, 10 to 19 nucleotide basepairs, 10 to 18 nucleotide basepairs, 10 to 17 nucleotide basepairs, or 10 to 16 nucleotide basepairs. In some embodiments, the barcoded nanoparticle complex has a polynucleotide detection tag with at least one coding region (i.e., a 1-position barcode). As understood by a person skilled in the art, the number of coding regions (n) corresponds to the number of different antigens that can be screened together and subsequently identified. For analysis of the coding regions in situ, the number of different coding regions is only limited by the number of different colored fluorescent dyes. For decoding of the polynucleotide detection tag, the coding regions will be “read” starting with coding region attached to the nanoparticle which is referred to as the first coding region or coding region 1. Any coding region thereafter in the direction away from the nanoparticle is the second coding region (coding region 2), followed by the third coding region (coding region 3) and so on. An example of a nanoparticle linked to a polynucleotide detection tag having three coding regions with a polynucleotide (e.g., ssDNA) hybridization domain (black) is depicted in
According to embodiments of the present invention, a polynucleotide hybridization domain is linked to the 3′ end of the polynucleotide detection tag of the barcoded NP, and a second polynucleotide hybridization domain is linked to the streptavidin scaffold of the antigen-MHC complex. Accordingly, the antigen-MHC complex is linked to a barcoded nanoparticle through hybridization of complementary hybridization domains. In some embodiments of the present invention, the first polynucleotide hybridization domain and the second polynucleotide hybridization domain may be single stranded DNA (ssDNA) having a first and a second hybridization sequence, respectively, where the first and second hybridization sequences are complementary, resulting in a linker of hybridized double stranded DNA (dsDNA), shown as overlapping black lines in
As understood by a person having ordinary skill in the art, each unique antigen-MHC complex is linked (i.e., hybridized) to a unique barcode sequence. In some embodiments of the present invention, the preparation of a barcoded NP-antigen-MHC complex library includes a record (e.g., a key or a legend) of the candidate antigens and their corresponding barcode (i.e., polynucleotide detection tag sequence). This coding key aides in efficiently identifying the specific antigens that pair with T cells. Examples of an antigen and barcode key for the list of candidate antigens (patient-specific candidate neoantigens and MART-1 tumor antigen) of
Embodiments of the present invention include a barcoded nanoparticle-antigen-MHC complex for use in screening antigen-specific T cells. As understood by a person skilled in the art, a single antigen may be assayed using the complex in the presence of T cells. However, assaying one candidate antigen is not as efficient as screening multiple candidate antigens. According to embodiments of the present invention, different barcoded NP antigen-MHC complexes are prepared using different candidate antigens with corresponding unique coding regions forming a library of barcoded NP-antigen-MHC complexes. The following methods are described using a library of the barcoded NP-antigen-MHC complexes; however the method may be followed or easily adapted for screening a single candidate antigen.
According to embodiments of the present invention, isolation and identification of patient-derived and antigen-specific T cells using a library of barcoded-NP-antigen-MHC complexes includes incubating the candidate antigen complexes with patient-derived T cells. In some embodiments, the patient-derived T cells are isolated from the patient's peripheral blood mononuclear cells (PBMCs) or tumor infiltrating lymphocytes (TILs). In some embodiments of the present invention, both CD4+ and CD8+ T cells are labeled and sorted from PBMCs or TILS using anti-CD4 and anti-CD8 fluorescent antibodies with live populations of CD4+ and CD8+ single-positive cells sorted using fluorescence-activated cell sorting (FACS), in order to isolate only CD4+ or CD8+ cells. In some embodiments of the present invention, T cells that are positive for both CD4 and CD8 may be isolated using an anti-CD3 fluorescent antibody followed by FACS. A person skilled in the art is able to determine the type of T cells to isolate for the type or types of antigen-MHC complex being used. For example, if the library is made exclusively of MHC I molecules, the T cell population may be only CD8+, whereas MCH II molecules would require CD4+ T cells. In other embodiments, an antigen library having both MHC I and MHC II molecules may be incubated with T cells that are both CD4 and CD8 positive. In still other embodiments, an antigen library having either MHC I or MHC II molecules may be screened with T cells that are positive for both CD4 and CD8.
Embodiments of the present invention include incubating a barcoded NP-antigen-MHC complex library with a suspension of CD4+, CD8+ or CD4+/CD8+ T cells. Incubation of the nanoparticle library with the T cell suspension allows for a complete and thorough exposure of the nanoparticle-bound antigen to the various T-cell receptors. This method may include rocking or rotation of the cells. Following incubation of the antigen complex and the T cells, the nanoparticle is selectively isolated or selectively collected. For example, if the nanoparticle is magnetic, applying a magnet to the suspension allows for separation of nanoparticles in a complex with antigen paired T cells and removal of unpaired T cells. An example of isolated magnetic nanoparticles with paired T cells is shown schematically in
For analysis of the paired T cells isolated with the nanoparticle complex, the cells are loaded into a microfluidic device that separates and posits single cells in individual locations (“traps”) in the channels of the device.
As used herein with respect to the barcoded nanoparticle antigen-MHC complex, “a paired T cell” and “a T cell paired antigen MHC complex” refers to the complex of a T cell having a T cell receptor epitope that binds to an antigen peptide in a barcoded nanoparticle antigen-MHC complex. Accordingly, with the paired T cells separated in the cell trapping device, the coding regions (barcodes) of the paired antigen-MHC complex are identified in situ to determine the sequence of the cognate peptide antigen. Accordingly, each coding region is read starting with coding region 1. All possible complementary polynucleotide sequences for coding region 1 are linked to a distinguishable fluorescent dye forming a dye-polynucleotide decoder sequence that hybridizes the fluorescence to the complementary coding region on the nanoparticle, thereby “reading” coding region 1. As used herein, a “distinguishable fluorescent dye,” and “distinguishable dye” refer to a dye of a color that is visually distinct from another dye. Any suitable dye may be used that is capable of being linked to a polynucleotide. In order to read the second coding region, a “displacement” polynucleotide is added to remove the dye-polynucleotide decoder of coding region 1 followed by or together with all of the possible dye-polynucleotide decoder sequences corresponding to coding region 2. In the decoding of more than one coding region, after coding region 1 is read, the polynucleotide detection tag is partially decoded.” That is, a “partially decoded polynucleotide detection tag” has at least one, but not all coding regions decoded. Subsequent coding regions are read using this read-displace/read-displace/read format. This step-wise readout technology was validated using barcoded particles as depicted and shown in
In some embodiments of the present invention, the coding regions (barcodes) of the T cell paired-antigen MHC complex are identified in situ using the fluorescent dye-polynucleotide decoding “reader” sequences in combination with the “displacement” polynucleotide sequences. This method was carried out using a barcoded NP-antigen-MHC library of the 27 antigens in
Embodiments of the present invention include a kit for preparing a library of barcoded nanoparticles, the kit including barcodes (polynucleotide detection tag) sequences, the corresponding fluorescent dye-linked polynucleotide decoder sequences for reading the barcodes, and the corresponding displacement polynucleotide sequences for removing the decoder sequences. The polynucleotide sequences include ssDNA or RNA. In some embodiments of the present invention the polynucleotide sequences are ssDNA. In some embodiments of the present invention, the polynucleotide detection tag sequences are modified at their 5′ end to a binding moiety for attachment to a nanoparticle. For example, the polynucleotide detection tag (ssDNA barcode) sequences in
In some embodiments of the present invention, a kit for preparing a library of barcoded nanoparticles also includes a recombinant conditional MHC tetramer complex capable of being loaded with any MHC antigen peptide. The MHC may be MHC Class I or MHC Class II and includes any specific haplotype corresponding to the patient's haplotype. For example, the kit may include MHC Class I molecules corresponding to an HLA type listed in Table 7. For example, the kit may include MHC Class II molecules corresponding to HLA-DM, HLA-DO, HLA-DQ, and HLA in which the MHC II a chain is encoded by the HLA-A-DMA, HLA-DOA, HLA-DPA1, HLA-DQA2, or HLA-DRA gene and the β chain is encoded by HLA-DMB, HLA-DOB, HLA-DPB1, HLA-DQB1, HLA-DQB2, HLA-DRB1, HLA-DRB3, HLA-DRB4, or HLA-DRB5 gene.
In some embodiments of the present invention, a kit for preparing a library of barcoded nanoparticles includes modified polynucleotide detection tag sequences for attachment to nanoparticles. Alternative methods for identifying the trapped barcoded T cell may be used. For example, the polynucleotide detection tag sequences may be amplified and sequenced from the microfluidic device.
Using the in situ decoding readout method for identifying the polynucleotide detection tag and the corresponding antigen paired with the trapped T cell, does not destroy or adversely affect the T cell. Accordingly, after the antigen has been identified, the trapped T cell may be removed from the microfluidic device for further analysis and/or growth.
The following Examples are presented for illustrative purposes only, and do not limit the scope or content of the present application.
EXAMPLES Example 1 Capture Efficiency of Antigen-Specific T CellsThe barcoded NP-antigen-MHC complex library was validated by employing selective capture of Mart-1 antigen specific T cells from a mixture of cells.
The NP-antigen-MHC complex library tool was used to analyze CD8+ cells expanded from tumor infiltrating lymphocytes (TILs) collected from on-treatment tumor biopsies of two metastatic melanoma cancer patients who were positively responding to anti-PD-1 checkpoint inhibitor therapy at the time of biopsy as shown in
The strongest binding 27 neoantigens for patient #1 are listed in
Some biospecimens were analyzed using a serial approach, in which each NP-barcoded NACS library element was used to query for a specific T cell population. This method is most useful for analysis of PBMCs, where neoantigen-specific T cell populations particularly rare scarce, and it can be challenging to remove all of the unbound magnetic NPs, which can interfere with the fluorescence read-out. To characterize the non-specific pulldown rate of this approach, the NP-barcoded NACS library designed for patient #1 was used to analyze expanded TILs from an additional unrelated melanoma patient on the same clinical trial, as well as PBMCs from a healthy volunteer. The list of neoantigens is unique for every patient, and so the library designed for patient #1 should not capture T cell populations for the two control patient samples. The results for both controls were similar: The patient #1 neo-antigen library captured on average 2 cells per library element, with a standard deviation of 1.4 as shown in
Example 4. Comparison with Multiplex Flow Analysis. The analysis of both patient's TILs revealed a larger number neoantigen-specific T cell populations than have been reported using multiplex flow analysis of similar patient samples. The expanded patient #1 TILs was analyzed using the multiplex flow method as described in Andersen et al., 2012, Nat. Protocols, 7:891-902, the entire contents of which are herein incorporated by reference. For this analysis, a 14-element tetramer library was prepared presenting putative neoantigens 1-8, 12, 14, 15, 19, 27 and Mart-1 (8 of which were detected using NP-barcoded NACS). Only T cells specific to neoantigen #12 were detected in only two colors and in >10 cells (
NACS method prompted analysis of peripheral blood from patient #1 for neoantigen-specific T cell populations. These T cells were not expanded in vitro, so as to avoid any population bias that can accompany such expansion. For the blood analysis, the full 50-element neoantigen library was used to interrogate PBMCs collected at four time points. Two time points (Days 187 and 208,
Day 41 PBMCs correspond to a time close to the biopsy from which the exome and transcriptome measurements were taken, but also during a period of pseudo-progression for patient #1 prior to response (
Several of the detected neoantigen-specific T cell populations from PBMCs correspond to relatively weak (Kd>100 nM) neoantigen/MHC binding affinities. The number of mutation-containing reads from the mRNAs associated with the mutated proteins from the pre-treatment transcriptome analysis are provided in the bottom graph of
Example 6. Captured T cells are Not Destroyed. An advantage to the NP-barcoded NACS method is that the process is non-destructive and single T-cells, now with known antigen-specificity, are individually isolated by the microfluidic device and available for further analysis, including TCR α and β gene sequencing. To this end, paired TCRα and TCRβ genes from a single T cell from patient #1 were cloned, both as proof of capability and validation of the barcoded neoantigen specificity. A CD8+ T cell was captured in the single microfluidic trapping device (
Analysis of T cells collected from two tumors of immunotherapy patients responding to anti-PD1 therapy reveals that around 20% of the top 50 predicted neoantigens account for a large fraction (˜7% for the HLA A*02.01) of CD8+ T cells in the tumor. The two patients analyzed here each express 6 HLA genotypes. Although the actual representation of additional HLA genotypes still needs to be tested, the implication is that 40% or more of the CD8+ TILs within these patient tumors are neoantigen specific. This number is significantly larger than would have been inferred using alternative analytic methods, and emphatically highlights the importance of neoantigen-specific T cell populations as major effectors in anti-PD-1 cancer immunotherapy. A second observation is that the measured spectrum of neoantigen-specific T cell populations only correlates loosely with the predicted rank-order of putative neoantigens. However, an additional correlation with mRNA expression levels was found, especially for the weaker binding neoantigens. A third observation is that the same neoantigen-specific populations detected in the tumor are also detected in the blood, albeit at a lower relative abundance to all CD8+ PBMCs. In the analysis reported here for patient #1, those populations are detected a full 2 months prior to traditional clinical measures (via in vivo imaging) of actual tumor shrinkage.
Example 7 Patients, Treatment, and Specimen CollectionPatients with metastatic melanoma were selected for the current analysis by being HLA-A*02:01 positive, having an adequate baseline biopsy as well as an on-treatment biopsy, and exhibiting an objective tumor response while participating in a phase 1 trial of pembrolizumab. Patients #1 and #2 received single agent pembrolizumab intravenously 10 mg/kg every 3 weeks (10Q3W). Tumor responses were evaluated starting at 12 weeks, confirmed 4 weeks after first response, and imaged every 12 weeks thereafter. Response was characterized by both the Response Evaluation Criteria in Solid Tumors (RECIST) and the immune-related response criteria (irRC). Tumour biopsy and peripheral blood cell collection and analyses were approved by UCLA IRBs 11-001918 and 11-003066. Tumor biopsies from the patients analyzed were obtained at baseline and on therapy and were processed with one aliquot immediately fixed in formalin followed by paraffin embedding for pathological analyses, a second aliquot snap frozen by immediate immersion in liquid nitrogen for genetic analyses, and a third aliquot minced fresh under sterile condition followed by DNAse/collagenase digestion to create single cell suspensions (s.c.s) before cryopreservation in liquid nitrogen. Peripheral blood mononuclear cells (PBMCs) were prepared from fresh whole blood by Ficoll-Paque density gradient centrifugation and cryopreserved.
Example 8 TIL Isolation and ExpansionTumor infiltrating lymphocytes were expanded from cryopreserved s.c.s using anti-CD3 antibody (OKT3, 50 ng/mL, 48 hr exposure) and IL-2 (300 IU/mL) and re-cyropreserved at 5×106 cells/mL after 2-4 weeks. TILs were thawed and treated with DNAse for 45 min the morning of use, and stained with antibodies to CD4 (BV510, BioLegend, San Diego, Calif.) and CD8+ (BV605, BioLegend, San Diego, Calif.). Live (7AAD-negative) populations of CD4 and CD8+ single-positive cells were sorted using a FACS Cell Sorter (BD Biosciences, San Jose, Calif.).
Example 9 Whole Exome Sequencing (WES), Mutation Calling and HLA-TypingBoth DNA and RNA were extracted simultaneously from snap-frozen tumor biopsies (Qiagen AllPrep Kit). DNA from tumors and matched normal blood samples were sequenced at the UCLA Clinical Microarray Core. Paired-end 2×100 bp sequencing was carried out on the Hi Seq 2000 platform (Illumina, San Diego, Calif.) following exon capture using the Nimblegen SeqCap EZ Human Exome Library v3.0 (Roche), which targets 65 Mb of genome. Sequencing generated 6-10 billion reads per sample, with each targeted base covered by an average of 90-150 reads. Sequences were aligned to the UCSC hg19 human genome reference using BWA-mem algorithm (v0.7.9). Preprocessing followed the GATK Best Practices Workflow v3, including duplicate removal (Picard Tools), indel realignment, and base quality score recalibration. Somatic mutations were called with methods modified from 1, using MuTect (v1.1.7)2, Varscan2 Somatic (v2.3.6)3, and the GATK-HaplotypeCaller (HC, v3.3). Only high-confidence mutations were retained, defined as those identified by at least two out of three programs. For the GATK-HC, somatic variants were determined using one-sided Fisher's Exact Test (P value cut-off ≦0.01) between tumor/normal pairs. Variants were annotated by Oncotator4, with non-synonymous mutations being those classified as Nonsense, Missense, Splice_Site, or Nonstop Mutations, as well as Frame_Shift, In_Frame, or Start_Codon altering insertions/deletions. HLA-typing was performed by ATHLATES from the whole exome sequencing data.
Example 10 RNA SequencingRNA sequencing was performed using the Illumina HiSeq 2500 platform on 100-bp paired-end libraries prepared using the IlluminaTruSeq RNA sample preparation kit per the manufacturer's instructions. Reads were mapped to hg19 using TopHat2 v2.0,5 and were quantified and normalized using Cufflinks v2.2.16 program and CuffNorm to generate normalized expression tables by library size (fragments per kilobase of exon per million fragments mapped, FPKM) using the geometric normalization method. Mutation-containing RNA reads were identified by a custom Python (v2.7.3) script utilizing the Biopython and pysam packages, and verified by visual inspection in the Integrated Genomics Viewer (IGV).
Example 11 Peptide HLA Binding Prediction and Neoantigen Candidate IdentificationPeptide binding predictions to HLA-A02:01 were generated by netMHC3.47 for 9-mer and 10-mer peptides in a sliding window around each non-synonymous amino acid-altering mutation. (Peptide sequences were derived from Ensembl GRCh37 release 74.) Candidate peptides were binned by 1) those with mutations-containing reads identified by RNA-seq, 2) those with RNA expression (FPKM>0) but no identified mutated reads, and 3) all others without detectable RNA-seq expression. Peptides were ranked and sorted by HLA binding affinity within each bin.
Example 12 Production of ssDNA-SAC ConjugatesThe ssDNA-SAC (strepatavidin antigen complex) conjugate was produced following previous published protocol as described in Kwong et al., 2009, J. Am. Chem Soc., 131:9695-9703, the entire contents of which are herein incorporated by reference. Briefly, SAC was first expressed from the pTSA-C plasmid containing the SAC gene (Addgene), as described in Sano et al., 1990, PNAS, 87:142-146, the entire content of which is herein incorporated by reference. Before conjugation to DNA, SAC (1 mg/ml) was buffer exchanged to PBS containing Tris(2-Carboxyethyl) phosphine Hydrochloride (TCEP, 5 mM) using zeba desalting columns (Pierce). Then MHPH (3-N-Maleimido-6-hydraziniumpyridine hydrochloride, 100 mM, Solulink) in DMF was added to SAC at a molar excess of 300:1. In the meantime, SFB (succinimidyl 4-formylbenzoate, 100 mM, Solulink) in DMF was added to 5′-amine modified ssDNA (500 uM) (5′-NH2-AAA AAA AAA A TAG GCA TCC CGA GGA TTC AG (SEQ ID NO: 157)) in a 40:1 molar ratio. After reacting at rt for 4 hours, MHPH-labeled SAC and SFB-labeled DNA were buffer exchanged to citrated (50 mM sodium citrate, 150 mM NaCl, pH 6.0), and then mixed in a 20:1 ratio of DNA to SAC to react at rt overnight. DNA-SAC conjugate was purified using the Superdex 200 gel filtration column (GE health) and concentrated with 10K MWCO ultra-centrifuge filters (Millipore).
Example 13 Human MHC Class I Neo-Antigen Library ConstructionMHC library was generated using the UV-mediated peptide exchange method as described in Rodenko et al., 2006, Nat. Protoc. 1:1120-1132, the entire content of which is herein incorporated by reference. The photo-labile peptide KILGFVFJV (SEQ ID NO: 158) and other neo-antigen peptides were synthesized with standard automated Fmoc-peptide synthesis methodology (J, (S)-3-(Fmoc-amino)-3-(2-nitrophenyl)propionic acid, is the photo-labile amino acid residue). Plasmids encoding human MHC class I heavy chain and human b2m containing bacterial strain were kind gifts from Ton N M Schumacher. MHC photo-labile protein was folded from MHC heavy chain inclusion body, b2m inclusion body and photo-labile peptide according to the previously published protocol 11 and then biotinylated using the BirA biotin ligase. Mixture of MHC photo-labile protein (0.5 uM) and neo-antigen peptide (50 uM) was exposed to 365 nm UV light for 1 hour to generate the MHC neo-antigen library.
Example 14 NP MHC Neo-Antigen Library ConstructionStreptavidin magnetic NP (1 um, ThermoFisher scientific) was mixed with biotin-DNA at 1:20 ratio to obtain NP-DNA. Excess DNA was removed by washing the magnetic NP for 3 times. In parallel, MHC neo-antigen library was added to ssDNA-SAC at 4:1 ratio to form the DNA-MHC tetramer. Equal amount (in terms of DNA ratio) of NP-DNA and DNA-MHC tetramer were hybridized at 37° C. for 30 min to generate the NP MHC neo-antigen library.
Example 15 Cell-Trapping Microfluidic Device FabricationFirst, a master mold with cell traps (multiple traps or single traps) was prepared using the SU-8 2025 photoresist. Sylgard 184 (A:B=10:1) mixture was then poured onto the mold, degassed and cured at 80° C. for 2 hours. In the meantime, a thin layer of PDMS was spun coated onto a glass slide at 2000 rpm/min and cured at 80° C. for 1 hour. The PDMS device and PDMS-coated glass were treated with O2 plasma for 1 min and bound together to get the final cell-trapping microfluidic device.
Example 16 TIL Pulldown and BarcodeNP MHC neo-antigen library was added to CD8+ human T cells for 30 min at rt. The NP-bound T cells were magnetically enriched and washed with PBS to remove any non-specifically pulled T cells. The cells were then loaded into costar transwell polycarbonate membrane (5 um pore) to remove free NPs. Then, the cells were loaded into the cell-trapping microfluidic device and sequentially barcoded. First, 3 different DNA-dyes (cy3, cy5 and Alex 488) were loaded to the device to hybridize with the DNA on the NP at 37° C. for 15 min. After a brief washing, fluorescent images were taken to obtain the first round barcode. Displacement DNAs were added to the device at 37° C. for 15 min to remove the first round DNA dyes. Similar procedures were employed to obtain the second and third round barcoding images.
Example 17 CD8+ T Cell Pulldown from PBMCCD8+ T cells from PBMC were sorted by FACS. CD8+ T cells were then (10K) stained with Calcein AM (ThermoFisher) and incubated with each individual NP-NACS library at rt for 30 min. Neo-antigen specific cells were enriched by magnet pulldown. The non-captured T cells in the supernatant was collected for further incubation with other NP-NACS library element. The enriched T cells were washed by PBS once to remove any non-specific cell pulldown. Cells were then loaded into the cell hemocytometer. The whole area in the hemocytometer chip was imaged to obtain the total pulldown cell number. Healthy donor PBMC and PBMC from an unrelated male melanoma patient were used as control to obtain the background.
Example 18 Single Cell TCR CloningNeo-antigen specific T cells were trapped in the microfluidic device with single cell traps (
To produce retrovirus, HEK-293T/17 cells were transfected via calcium phosphate precipitation with the TCR vector, a packaging vector encoding gag-pol, and a pseudotyping vector encoding RD114 envelope glycoprotein. Media was replaced 24 hours following transfection and viral supernatant was collected 48 hours following transfection. An equal volume of viral supernatant was added to Jurkat T cells in RPMI-based medium (final density: 0.5×106 cells/mL) and polybrene was added to a final concentration of 5 μg/mL. Cells were spinfected at 1350×g for 90 minutes at 30° C., and then incubated with virus overnight at 37° C., 5% CO2. Half of the media was replaced 24 hours following infection and cells were assayed for TCR specificity 48 hours following infection via flow cytometry using cognate fluorescent peptide-MHC tetramers.
Example 19 MHC I HLA Subtypes
While the present invention has been illustrated and described with reference to certain exemplary embodiments, those of ordinary skill in the art will understand that various modifications and changes may be made to the described embodiments without departing from the spirit and scope of the present invention, as defined in the following claims.
Claims
1. An antigen complex, comprising:
- a nanoparticle sorting agent comprising: a nanoparticle; a polynucleotide detection tag having at least one coding region, the polynucleotide detection tag being conjugated to the nanoparticle; and a first polynucleotide hybridization domain conjugated to the polynucleotide detection tag; and
- a peptide-loaded streptavidin major histocompatability complex (MHC) tetramer, comprising: a modified streptavidin protein; four biotin-modified MHC proteins each independently conjugated to the modified streptavidin protein; an antigen peptide bound to the biotin-modified MHC proteins; and a second polynucleotide hybridization domain different from the first polynucleotide hybridization domain and conjugated to the modified streptavidin protein,
- the nanoparticle sorting agent being linked to the peptide-loaded streptavidin MHC tetramer by hybridization of the first polynucleotide hybridization domain to the second polynucleotide hybridization domain.
2. The antigen complex of claim 1, wherein the modified streptavidin protein is modified with a binding moiety selected from the group consisting of a cysteine, a thiol group, maleimide group, an adamantane group, a cyclodextrin group, an amine group, a carboxy group, an azide group, and an alkyne group.
3. The antigen complex of claim 1, wherein the modified streptavidin protein is modified with cysteine.
4. The antigen complex of claim 1, wherein the second polynucleotide hybridization domain is modified with a binding moiety selected from the group consisting of a cysteine, a thiol group, maleimide group, an adamantane group, a cyclodextrin group, an amine group, a carboxy group, an azide group, and an alkyne group.
5. The antigen complex of claim 1, wherein the second polynucleotide hybridization domain is modified with maleimide.
6. The antigen complex of claim 1, wherein the nanoparticle is a magnetic nanoparticle or a polystyrene nanoparticle.
7. The antigen complex of claim 1, wherein the at least one coding region of the polynucleotide detection tag comprises at least three different coding regions.
8. The antigen complex of claim 1, wherein the nanoparticle is modified with a binding moiety selected from the group consisting of streptavidin, biotin, a cysteine, a thiol group, maleimide group, an adamantane group, a cyclodextrin group, an amine group, a carboxy group, an azide group, and an alkyne group.
9. The antigen complex of claim 1, wherein the nanoparticle is modified with streptavidin and the polynucleotide detection tag is modified with biotin.
10. The antigen complex of claim 1, wherein the antigen peptide is selected from the group consisting of tumor antigens, tumor neoantigens, viral antigens, phosphoantigens, and combinations thereof.
11. A library of antigen complexes, comprising:
- a plurality of antigen complexes of claim 1, each of the antigen complexes having a different antigen peptide and different polynucleotide detection tag than any other of the antigen complexes in the plurality of antigen complexes.
12. A kit for detecting neoantigen-specific T cells, comprising:
- a polynucleotide detection tag comprising at least one coding region, the polynucleotide detection tag being conjugated to a nanoparticle; and
- a decoding polynucleotide that is capable of hybridizing to the at least one coding region of the polynucleotide detection tag.
13. The kit of claim 12, wherein the decoding polynucleotide is a labeled decoding polynucleotide, the kit further comprising:
- a displacement polynucleotide capable of hybridizing to the decoding polynucleotide.
14. The kit of claim 12, further comprising a peptide-loaded streptavidin major histocompatability complex (MHC) tetramer, comprising:
- a modified streptavidin protein;
- four biotin-modified MHC proteins each independently conjugated to the modified streptavidin protein; and
- an antigen peptide bound to the biotin-modified MHC proteins.
15. The kit of claim 13, wherein the labeled decoding polynucleotide comprises a nucleotide sequence conjugated to a distinguishable fluorescent dye.
16. A method for isolating neo-antigen-specific T cells for a tumor in a subject, comprising:
- identifying candidate T cell epitopes for the tumor using a major histocompatiblity complex (MHC) binding algorithm;
- synthesizing antigen peptides corresponding to the candidate T cell epitopes;
- preparing the library of antigen complexes of claim 11 using the antigen peptides;
- incubating the library of antigen complexes with TILs or PBMCs from the subject; and
- separating paired T cells from unpaired T cells, the paired T cells comprising those T cells that have paired with any of the antigen peptides of any of the antigen complexes in the library of antigen complexes.
17. The method of claim 16, wherein identifying candidate T cell epitopes comprises acquiring the genome or exome sequence of the tumor.
18. The method of claim 16, further comprising:
- adding the paired T cells to a microfluidic device to separate the paired T cells into individual paired T cells; and
- detecting the sequence of the at least one coding region of the polynucleotide detection tag of the antigen complex of each individual paired T cell.
19. The method of claim 18, wherein the detecting the sequence of the at least one coding region of the polynucleotide detection tag of the antigen complex of each individual paired T cell comprises:
- Incubating the polynucleotide detection tag of each individual paired T cell with at least two labeled decoding polynucleotides; and
- detecting presence of a hybridized labeled decoding polynucleotide to thereby determine the sequence of the at least one coding region of the polynucleotide detection tag.
20. The method of claim 18, wherein the least one coding region of the polynucleotide detection tag of the antigen complex comprises at least two coding regions, and the detecting the sequence of the at least two coding regions of the polynucleotide detection tag of the antigen complex of each individual paired T cell comprises:
- incubating the polynucleotide detection tag of each individual paired T cell with at least two first labeled decoding polynucleotides;
- detecting presence of one or more first hybridized labeled decoding polynucleotides to thereby determine the sequence of a first one of the at least two coding regions of the polynucleotide detection tag;
- incubating the one or more first hybridized labeled decoding polynucleotides with one or more displacement polynucleotides to remove the first labeled decoding polynucleotides from the first hybridized labeled decoding polynucleotide to yield a partially decoded polynucleotide detection tag;
- incubating the partially decoded polynucleotide detection tag with one or more second labeled decoding polynucleotides; and
- detecting presence of a second hybridized labeled decoding polynucleotide to thereby determine the sequence of a second one of the at least two coding regions of the polynucleotide detection tag of the antigen complex of each individual paired T cell.
Type: Application
Filed: Jun 1, 2016
Publication Date: Jan 5, 2017
Patent Grant number: 10481158
Inventors: James R. Heath (South Pasadena, CA), Songming Peng (Pasadena, CA)
Application Number: 15/170,919
